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這篇文章主要介紹 Redis 集群的示例分析，文中介紹的非常詳細(xì)，具有一定的參考價(jià)值，感興趣的小伙伴們一定要看完！
Redis 集群詳解
Redis 有三種集群模式，分別是：
* 主從模式
* Sentinel 模式
* Cluster 模式三種集群模式各有特點(diǎn)，關(guān)于 Redis 介紹可以參考這里：NoSQL（二)——Redis
Redis 官網(wǎng)：https://redis.io/，最新版本 5.0.4
主從模式
主從模式介紹
主從模式是三種模式中最簡(jiǎn)單的，在主從復(fù)制中，數(shù)據(jù)庫(kù)分為兩類：主數(shù)據(jù)庫(kù) (master) 和從數(shù)據(jù)庫(kù)(slave)。
其中主從復(fù)制有如下特點(diǎn)：
* 主數(shù)據(jù)庫(kù)可以進(jìn)行讀寫(xiě)操作，當(dāng)讀寫(xiě)操作導(dǎo)致數(shù)據(jù)變化時(shí)會(huì)自動(dòng)將數(shù)據(jù)同步給從數(shù)據(jù)庫(kù)
* 從數(shù)據(jù)庫(kù)一般都是只讀的，并且接收主數(shù)據(jù)庫(kù)同步過(guò)來(lái)的數(shù)據(jù)
* 一個(gè) master 可以擁有多個(gè) slave，但是一個(gè) slave 只能對(duì)應(yīng)一個(gè) master
* slave 掛了不影響其他 slave 的讀和 master 的讀和寫(xiě)，重新啟動(dòng)后會(huì)將數(shù)據(jù)從 master 同步過(guò)來(lái)
* master 掛了以后，不影響 slave 的讀，但 redis 不再提供寫(xiě)服務(wù)，master 重啟后 redis 將重新對(duì)外提供寫(xiě)服務(wù)
* master 掛了以后，不會(huì)在 slave 節(jié)點(diǎn)中重新選一個(gè) master工作機(jī)制：
當(dāng) slave 啟動(dòng)后，主動(dòng)向 master 發(fā)送 SYNC 命令。master 接收到 SYNC 命令后在后臺(tái)保存快照（RDB 持久化）和緩存保存快照這段時(shí)間的命令，然后將保存的快照文件和緩存的命令發(fā)送給 slave。slave 接收到快照文件和命令后加載快照文件和緩存的執(zhí)行命令。
復(fù)制初始化后，master 每次接收到的寫(xiě)命令都會(huì)同步發(fā)送給 slave，保證主從數(shù)據(jù)一致性。
安全設(shè)置：
當(dāng) master 節(jié)點(diǎn)設(shè)置密碼后，
客戶端訪問(wèn) master 需要密碼
啟動(dòng) slave 需要密碼，在配置文件中配置即可
客戶端訪問(wèn) slave 不需要密碼缺點(diǎn)：
從上面可以看出，master 節(jié)點(diǎn)在主從模式中唯一，若 master 掛掉，則 redis 無(wú)法對(duì)外提供寫(xiě)服務(wù)。
主從模式搭建
環(huán)境準(zhǔn)備：
master 節(jié)點(diǎn) 192.168.30.128
slave 節(jié)點(diǎn) 192.168.30.129
slave 節(jié)點(diǎn) 192.168.30.130全部下載安裝：
# cd /software# wget http://download.redis.io/releases/redis-5.0.4.tar.gz# tar zxf redis-5.0.4.tar.gz mv redis-5.0.4/ /usr/local/redis# cd /usr/local/redis make make install# echo $?0全部配置成服務(wù)：
服務(wù)文件
# vim /usr/lib/systemd/system/redis.service[Unit]Description=Redis persistent key-value database
After=network.target
After=network-online.target
Wants=network-online.target[Service]ExecStart=/usr/local/bin/redis-server /usr/local/redis/redis.conf --supervised systemd
ExecStop=/usr/libexec/redis-shutdown
Type=notify
User=redis
Group=redis
RuntimeDirectory=redis
RuntimeDirectoryMode=0755[Install]WantedBy=multi-user.targetshutdown 腳本
# vim /usr/libexec/redis-shutdown#!/bin/bash## Wrapper to close properly redis and sentineltest x $REDIS_DEBUG != x set -x
REDIS_CLI=/usr/local/bin/redis-cli# Retrieve service nameSERVICE_NAME= $1 if [ -z $SERVICE_NAME ]; then
SERVICE_NAME=redisfi# Get the proper config file based on service nameCONFIG_FILE= /usr/local/redis/$SERVICE_NAME.conf # Use awk to retrieve host, port from config fileHOST=`awk /^[[:blank:]]*bind/ { print $2 } $CONFIG_FILE | tail -n1`PORT=`awk /^[[:blank:]]*port/ { print $2 } $CONFIG_FILE | tail -n1`PASS=`awk /^[[:blank:]]*requirepass/ { print $2 } $CONFIG_FILE | tail -n1`SOCK=`awk /^[[:blank:]]*unixsocket\s/ { print $2 } $CONFIG_FILE | tail -n1`# Just in case, use default host, portHOST=${HOST:-127.0.0.1}if [ $SERVICE_NAME = redis ]; then
PORT=${PORT:-6379}else
PORT=${PORT:-26739}fi# Setup additional parameters# e.g password-protected redis instances[ -z $PASS ] || ADDITIONAL_PARAMS= -a $PASS # shutdown the service properlyif [ -e $SOCK ] ; then
$REDIS_CLI -s $SOCK $ADDITIONAL_PARAMS shutdownelse
$REDIS_CLI -h $HOST -p $PORT $ADDITIONAL_PARAMS shutdownfi# chmod +x /usr/libexec/redis-shutdown# useradd -s /sbin/nologin redis# chown -R redis:redis /usr/local/redis# chown -R redis:redis /data/redis# yum install -y bash-completion source /etc/profile # 命令補(bǔ)全 # systemctl daemon-reload# systemctl enable redis修改配置：
192.168.30.128
# mkdir -p /data/redis# vim /usr/local/redis/redis.confbind 192.168.30.128 #監(jiān)聽(tīng) ip，多個(gè) ip 用空格分隔 daemonize yes # 允許后臺(tái)啟動(dòng) logfile /usr/local/redis/redis.log #日志路徑 dir /data/redis #數(shù)據(jù)庫(kù)備份文件存放目錄 masterauth 123456 #slave 連接 master 密碼，master 可省略 requirepass 123456 #設(shè)置 master 連接密碼，slave 可省略 appendonly yes # 在 /data/redis/ 目錄生成 appendonly.aof 文件，將每一次寫(xiě)操作請(qǐng)求都追加到 appendonly.aof 文件中 # echo vm.overcommit_memory=1 /etc/sysctl.conf# sysctl -p192.168.30.129
# mkdir -p /data/redis# vim /usr/local/redis/redis.confbind 192.168.30.129
daemonize yeslogfile /usr/local/redis/redis.log dir /data/redis
replicaof 192.168.30.128 6379
masterauth 123456
requirepass 123456
appendonly yes# echo vm.overcommit_memory=1 /etc/sysctl.conf# sysctl -p192.168.30.130
# mkdir -p /data/redis# vim /usr/local/redis/redis.confbind 192.168.30.130
daemonize yeslogfile /usr/local/redis/redis.log dir /data/redis
replicaof 192.168.30.128 6379
masterauth 123456
requirepass 123456
appendonly yes# echo vm.overcommit_memory=1 /etc/sysctl.conf# sysctl -p全部啟動(dòng) redis：
# systemctl start redis查看集群狀態(tài)：
# redis-cli -h 192.168.30.128 -a 123456Warning: Using a password with -a or -u option on the command line interface may not be safe.
192.168.30.128:6379 info replication# Replicationrole:master
connected_slaves:2
slave0:ip=192.168.30.129,port=6379,state=online,offset=168,lag=1
slave1:ip=192.168.30.130,port=6379,state=online,offset=168,lag=1
master_replid:fb4941e02d5032ad74c6e2383211fc58963dbe90
master_replid2:0000000000000000000000000000000000000000
master_repl_offset:168
second_repl_offset:-1
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:1
repl_backlog_histlen:168# redis-cli -h 192.168.30.129 -a 123456 info replicationWarning: Using a password with -a or -u option on the command line interface may not be safe.# Replicationrole:slave
master_host:192.168.30.128
master_port:6379
master_link_status:up
master_last_io_seconds_ago:1
master_sync_in_progress:0
slave_repl_offset:196
slave_priority:100
slave_read_only:1
connected_slaves:0
master_replid:fb4941e02d5032ad74c6e2383211fc58963dbe90
master_replid2:0000000000000000000000000000000000000000
master_repl_offset:196
second_repl_offset:-1
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:1
repl_backlog_histlen:196數(shù)據(jù)演示：
192.168.30.128:6379 keys *(empty list or set)192.168.30.128:6379 set key1 100
192.168.30.128:6379 set key2 lzx
192.168.30.128:6379 keys *
1) key1 2) key2# redis-cli -h 192.168.30.129 -a 123456Warning: Using a password with -a or -u option on the command line interface may not be safe.
192.168.30.129:6379 keys *
1) key2 2) key1 192.168.30.129:6379 CONFIG GET dir1) dir 2) /data/redis 192.168.30.129:6379 CONFIG GET dbfilename
1) dbfilename 2) dump.rdb 192.168.30.129:6379 get key1 100 192.168.30.129:6379 get key2 lzx 192.168.30.129:6379 set key3 aaa(error) READONLY You can t write against a read only replica.# redis-cli -h 192.168.30.130 -a 123456Warning: Using a password with -a or -u option on the command line interface may not be safe.
192.168.30.130:6379 keys *
1) key2 2) key1 192.168.30.130:6379 CONFIG GET dir1) dir 2) /data/redis 192.168.30.130:6379 CONFIG GET dbfilename
1) dbfilename 2) dump.rdb 192.168.30.130:6379 get key1 100 192.168.30.130:6379 get key2 lzx 192.168.30.130:6379 set key3 aaa(error) READONLY You can t write against a read only replica.可以看到，在 master 節(jié)點(diǎn)寫(xiě)入的數(shù)據(jù)，很快就同步到 slave 節(jié)點(diǎn)上，而且在 slave 節(jié)點(diǎn)上無(wú)法寫(xiě)入數(shù)據(jù)。
Sentinel 模式 Sentinel 模式介紹
主從模式的弊端就是不具備高可用性，當(dāng) master 掛掉以后，Redis 將不能再對(duì)外提供寫(xiě)入操作，因此 sentinel 應(yīng)運(yùn)而生。
sentinel 中文含義為哨兵，顧名思義，它的作用就是監(jiān)控 redis 集群的運(yùn)行狀況，特點(diǎn)如下：
* sentinel 模式是建立在主從模式的基礎(chǔ)上，如果只有一個(gè) Redis 節(jié)點(diǎn)，sentinel 就沒(méi)有任何意義
* 當(dāng) master 掛了以后，sentinel 會(huì)在 slave 中選擇一個(gè)做為 master，并修改它們的配置文件，其他 slave 的配置文件也會(huì)被修改，比如 slaveof 屬性會(huì)指向新的 master
* 當(dāng) master 重新啟動(dòng)后，它將不再是 master 而是做為 slave 接收新的 master 的同步數(shù)據(jù)
* sentinel 因?yàn)橐彩且粋€(gè)進(jìn)程有掛掉的可能，所以 sentinel 也會(huì)啟動(dòng)多個(gè)形成一個(gè) sentinel 集群
* 多 sentinel 配置的時(shí)候，sentinel 之間也會(huì)自動(dòng)監(jiān)控
* 當(dāng)主從模式配置密碼時(shí)，sentinel 也會(huì)同步將配置信息修改到配置文件中，不需要擔(dān)心
* 一個(gè) sentinel 或 sentinel 集群可以管理多個(gè)主從 Redis，多個(gè) sentinel 也可以監(jiān)控同一個(gè) redis
* sentinel 最好不要和 Redis 部署在同一臺(tái)機(jī)器，不然 Redis 的服務(wù)器掛了以后，sentinel 也掛了工作機(jī)制：
* 每個(gè) sentinel 以每秒鐘一次的頻率向它所知的 master，slave 以及其他 sentinel 實(shí)例發(fā)送一個(gè) PING 命令
* 如果一個(gè)實(shí)例距離最后一次有效回復(fù) PING 命令的時(shí)間超過(guò) down-after-milliseconds 選項(xiàng)所指定的值， 則這個(gè)實(shí)例會(huì)被 sentinel 標(biāo)記為主觀下線。
* 如果一個(gè) master 被標(biāo)記為主觀下線，則正在監(jiān)視這個(gè) master 的所有 sentinel 要以每秒一次的頻率確認(rèn) master 的確進(jìn)入了主觀下線狀態(tài)
* 當(dāng)有足夠數(shù)量的 sentinel（大于等于配置文件指定的值）在指定的時(shí)間范圍內(nèi)確認(rèn) master 的確進(jìn)入了主觀下線狀態(tài)， 則 master 會(huì)被標(biāo)記為客觀下線
* 在一般情況下， 每個(gè) sentinel 會(huì)以每 10 秒一次的頻率向它已知的所有 master，slave 發(fā)送 INFO 命令
* 當(dāng) master 被 sentinel 標(biāo)記為客觀下線時(shí)，sentinel 向下線的 master 的所有 slave 發(fā)送 INFO 命令的頻率會(huì)從 10 秒一次改為 1 秒一次
* 若沒(méi)有足夠數(shù)量的 sentinel 同意 master 已經(jīng)下線，master 的客觀下線狀態(tài)就會(huì)被移除； 若 master 重新向 sentinel 的 PING 命令返回有效回復(fù)，master 的主觀下線狀態(tài)就會(huì)被移除當(dāng)使用 sentinel 模式的時(shí)候，客戶端就不要直接連接 Redis，而是連接 sentinel 的 ip 和 port，由 sentinel 來(lái)提供具體的可提供服務(wù)的 Redis 實(shí)現(xiàn)，這樣當(dāng) master 節(jié)點(diǎn)掛掉以后，sentinel 就會(huì)感知并將新的 master 節(jié)點(diǎn)提供給使用者。
Sentinel 模式搭建
環(huán)境準(zhǔn)備：
master 節(jié)點(diǎn) 192.168.30.128 sentinel 端口：26379
slave 節(jié)點(diǎn) 192.168.30.129 sentinel 端口：26379
slave 節(jié)點(diǎn) 192.168.30.130 sentinel 端口：26379修改配置：
前面已經(jīng)下載安裝了 redis，這里省略，直接修改 sentinel 配置文件。
192.168.30.128
# vim /usr/local/redis/sentinel.confdaemonize yeslogfile /usr/local/redis/sentinel.log dir /usr/local/redis/sentinel #sentinel 工作目錄 sentinel monitor mymaster 192.168.30.128 6379 2 # 判斷 master 失效至少需要 2 個(gè) sentinel 同意，建議設(shè)置為 n /2+1，n 為 sentinel 個(gè)數(shù) sentinel auth-pass mymaster 123456
sentinel down-after-milliseconds mymaster 30000 # 判斷 master 主觀下線時(shí)間，默認(rèn) 30s這里需要注意，sentinel auth-pass mymaster 123456 需要配置在 sentinel monitor mymaster 192.168.30.128 6379 2 下面，否則啟動(dòng)報(bào)錯(cuò)：
# /usr/local/bin/redis-sentinel /usr/local/redis/sentinel.conf*** FATAL CONFIG FILE ERROR ***
Reading the configuration file, at line 104 sentinel auth-pass mymaster 123456 No such master with specified name.全部啟動(dòng) sentinel：
# mkdir /usr/local/redis/sentinel chown -R redis:redis /usr/local/redis# /usr/local/bin/redis-sentinel /usr/local/redis/sentinel.conf任一主機(jī)查看日志：
# tail -f /usr/local/redis/sentinel.log21574:X 09 May 2019 15:32:04.298 # Sentinel ID is 30c417116a8edbab09708037366c4a7471beb77021574:X 09 May 2019 15:32:04.298 # +monitor master mymaster 192.168.30.128 6379 quorum 221574:X 09 May 2019 15:32:04.299 * +slave slave 192.168.30.129:6379 192.168.30.129 6379 @ mymaster 192.168.30.128 6379
21574:X 09 May 2019 15:32:04.300 * +slave slave 192.168.30.130:6379 192.168.30.130 6379 @ mymaster 192.168.30.128 6379
21574:X 09 May 2019 15:32:16.347 * +sentinel sentinel 79b8d61626afd4d059fb5a6a63393e9a1374e78f 192.168.30.129 26379 @ mymaster 192.168.30.128 6379
21574:X 09 May 2019 15:32:31.584 * +sentinel sentinel d7b429dcba792103ef0d80827dd0910bd9284d21 192.168.30.130 26379 @ mymaster 192.168.30.128 6379Sentinel 模式下的幾個(gè)事件：
· +reset-master ：主服務(wù)器已被重置。· +slave ：一個(gè)新的從服務(wù)器已經(jīng)被 Sentinel 識(shí)別并關(guān)聯(lián)。· +failover-state-reconf-slaves ：故障轉(zhuǎn)移狀態(tài)切換到了 reconf-slaves 狀態(tài)。· +failover-detected ：另一個(gè) Sentinel 開(kāi)始了一次故障轉(zhuǎn)移操作，或者一個(gè)從服務(wù)器轉(zhuǎn)換成了主服務(wù)器。· +slave-reconf-sent ：領(lǐng)頭（leader）的 Sentinel 向?qū)嵗l(fā)送了 [SLAVEOF](/commands/slaveof.html) 命令，為實(shí)例設(shè)置新的主服務(wù)器。· +slave-reconf-inprog ：實(shí)例正在將自己設(shè)置為指定主服務(wù)器的從服務(wù)器，但相應(yīng)的同步過(guò)程仍未完成。· +slave-reconf-done ：從服務(wù)器已經(jīng)成功完成對(duì)新主服務(wù)器的同步。· -dup-sentinel ：對(duì)給定主服務(wù)器進(jìn)行監(jiān)視的一個(gè)或多個(gè) Sentinel 已經(jīng)因?yàn)橹貜?fù)出現(xiàn)而被移除 —— 當(dāng) Sentinel 實(shí)例重啟的時(shí)候，就會(huì)出現(xiàn)這種情況。· +sentinel ：一個(gè)監(jiān)視給定主服務(wù)器的新 Sentinel 已經(jīng)被識(shí)別并添加。· +sdown ：給定的實(shí)例現(xiàn)在處于主觀下線狀態(tài)。· -sdown ：給定的實(shí)例已經(jīng)不再處于主觀下線狀態(tài)。· +odown ：給定的實(shí)例現(xiàn)在處于客觀下線狀態(tài)。· -odown ：給定的實(shí)例已經(jīng)不再處于客觀下線狀態(tài)。· +new-epoch ：當(dāng)前的紀(jì)元（epoch）已經(jīng)被更新。· +try-failover ：一個(gè)新的故障遷移操作正在執(zhí)行中，等待被大多數(shù) Sentinel 選中（waiting to be elected by the majority）。· +elected-leader ：贏得指定紀(jì)元的選舉，可以進(jìn)行故障遷移操作了。· +failover-state-select-slave ：故障轉(zhuǎn)移操作現(xiàn)在處于 select-slave 狀態(tài) —— Sentinel 正在尋找可以升級(jí)為主服務(wù)器的從服務(wù)器。· no-good-slave ：Sentinel 操作未能找到適合進(jìn)行升級(jí)的從服務(wù)器。Sentinel 會(huì)在一段時(shí)間之后再次嘗試尋找合適的從服務(wù)器來(lái)進(jìn)行升級(jí)，又或者直接放棄執(zhí)行故障轉(zhuǎn)移操作。· selected-slave ：Sentinel 順利找到適合進(jìn)行升級(jí)的從服務(wù)器。· failover-state-send-slaveof-noone ：Sentinel 正在將指定的從服務(wù)器升級(jí)為主服務(wù)器，等待升級(jí)功能完成。· failover-end-for-timeout ：故障轉(zhuǎn)移因?yàn)槌瑫r(shí)而中止，不過(guò)最終所有從服務(wù)器都會(huì)開(kāi)始復(fù)制新的主服務(wù)器（slaves will eventually be configured to replicate with the new master anyway）。· failover-end ：故障轉(zhuǎn)移操作順利完成。所有從服務(wù)器都開(kāi)始復(fù)制新的主服務(wù)器了。· +switch-master ：配置變更，主服務(wù)器的 IP 和地址已經(jīng)改變。 這是絕大多數(shù)外部用戶都關(guān)心的信息。· +tilt ：進(jìn)入 tilt 模式。· -tilt ：退出 tilt 模式。master 宕機(jī)演示：
192.168.30.128
# systemctl stop redis# tail -f /usr/local/redis/sentinel.log22428:X 09 May 2019 15:51:29.287 # +sdown master mymaster 192.168.30.128 637922428:X 09 May 2019 15:51:29.371 # +odown master mymaster 192.168.30.128 6379 #quorum 2/222428:X 09 May 2019 15:51:29.371 # +new-epoch 122428:X 09 May 2019 15:51:29.371 # +try-failover master mymaster 192.168.30.128 637922428:X 09 May 2019 15:51:29.385 # +vote-for-leader 30c417116a8edbab09708037366c4a7471beb770 122428:X 09 May 2019 15:51:29.403 # d7b429dcba792103ef0d80827dd0910bd9284d21 voted for 30c417116a8edbab09708037366c4a7471beb770 122428:X 09 May 2019 15:51:29.408 # 79b8d61626afd4d059fb5a6a63393e9a1374e78f voted for 30c417116a8edbab09708037366c4a7471beb770 122428:X 09 May 2019 15:51:29.451 # +elected-leader master mymaster 192.168.30.128 637922428:X 09 May 2019 15:51:29.451 # +failover-state-select-slave master mymaster 192.168.30.128 637922428:X 09 May 2019 15:51:29.528 # +selected-slave slave 192.168.30.129:6379 192.168.30.129 6379 @ mymaster 192.168.30.128 637922428:X 09 May 2019 15:51:29.528 * +failover-state-send-slaveof-noone slave 192.168.30.129:6379 192.168.30.129 6379 @ mymaster 192.168.30.128 6379
22428:X 09 May 2019 15:51:29.594 * +failover-state-wait-promotion slave 192.168.30.129:6379 192.168.30.129 6379 @ mymaster 192.168.30.128 6379
22428:X 09 May 2019 15:51:30.190 # +promoted-slave slave 192.168.30.129:6379 192.168.30.129 6379 @ mymaster 192.168.30.128 637922428:X 09 May 2019 15:51:30.190 # +failover-state-reconf-slaves master mymaster 192.168.30.128 637922428:X 09 May 2019 15:51:30.258 * +slave-reconf-sent slave 192.168.30.130:6379 192.168.30.130 6379 @ mymaster 192.168.30.128 6379
22428:X 09 May 2019 15:51:30.511 # -odown master mymaster 192.168.30.128 637922428:X 09 May 2019 15:51:31.233 * +slave-reconf-inprog slave 192.168.30.130:6379 192.168.30.130 6379 @ mymaster 192.168.30.128 6379
22428:X 09 May 2019 15:51:31.233 * +slave-reconf-done slave 192.168.30.130:6379 192.168.30.130 6379 @ mymaster 192.168.30.128 6379
22428:X 09 May 2019 15:51:31.297 # +failover-end master mymaster 192.168.30.128 637922428:X 09 May 2019 15:51:31.297 # +switch-master mymaster 192.168.30.128 6379 192.168.30.129 637922428:X 09 May 2019 15:51:31.298 * +slave slave 192.168.30.130:6379 192.168.30.130 6379 @ mymaster 192.168.30.129 6379
22428:X 09 May 2019 15:51:31.298 * +slave slave 192.168.30.128:6379 192.168.30.128 6379 @ mymaster 192.168.30.129 6379
22428:X 09 May 2019 15:52:31.307 # +sdown slave 192.168.30.128:6379 192.168.30.128 6379 @ mymaster 192.168.30.129 6379從日志中可以看到，master 已經(jīng)從 192.168.30.128 轉(zhuǎn)移到 192.168.30.129 上
192.168.30.129 上查看集群信息
# /usr/local/bin/redis-cli -h 192.168.30.129 -p 6379 -a 123456Warning: Using a password with -a or -u option on the command line interface may not be safe.
192.168.30.129:6379 info replication# Replicationrole:master
connected_slaves:1
slave0:ip=192.168.30.130,port=6379,state=online,offset=291039,lag=1
master_replid:757aff269236ed2707ba584a86a40716c1c76d74
master_replid2:47a862fc0ff20362be29096ecdcca6d432070ee9
master_repl_offset:291182
second_repl_offset:248123
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:1
repl_backlog_histlen:291182
192.168.30.129:6379 set key4 linux
OK當(dāng)前集群中只有一個(gè) slave——192.168.30.130，master 是 192.168.30.129，且 192.168.30.129 具有寫(xiě)權(quán)限。
192.168.30.130 上查看 redis 的配置文件也可以看到 replicaof 192.168.30.129 6379，這是 sentinel 在選舉 master 是做的修改。
重新把 192.168.30.128 上進(jìn)程啟動(dòng)
# systemctl start redis# tail -f /usr/local/redis/sentinel.log22428:X 09 May 2019 15:51:31.297 # +switch-master mymaster 192.168.30.128 6379 192.168.30.129 637922428:X 09 May 2019 15:51:31.298 * +slave slave 192.168.30.130:6379 192.168.30.130 6379 @ mymaster 192.168.30.129 6379
22428:X 09 May 2019 15:51:31.298 * +slave slave 192.168.30.128:6379 192.168.30.128 6379 @ mymaster 192.168.30.129 6379
22428:X 09 May 2019 15:52:31.307 # +sdown slave 192.168.30.128:6379 192.168.30.128 6379 @ mymaster 192.168.30.129 637922428:X 09 May 2019 16:01:24.872 # -sdown slave 192.168.30.128:6379 192.168.30.128 6379 @ mymaster 192.168.30.129 6379查看集群信息
# /usr/local/bin/redis-cli -h 192.168.30.128 -p 6379 -a 123456Warning: Using a password with -a or -u option on the command line interface may not be safe.
192.168.30.128:6379 info replication# Replicationrole:slave
master_host:192.168.30.129
master_port:6379
master_link_status:up
master_last_io_seconds_ago:0
master_sync_in_progress:0
slave_repl_offset:514774
slave_priority:100
slave_read_only:1
connected_slaves:0
master_replid:757aff269236ed2707ba584a86a40716c1c76d74
master_replid2:0000000000000000000000000000000000000000
master_repl_offset:514774
second_repl_offset:-1
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:376528
repl_backlog_histlen:138247
192.168.30.128:6379 get key4 linux 192.168.30.128:6379 set key5(error) ERR wrong number of arguments for set command即使 192.168.30.128 重新啟動(dòng) redis 服務(wù)，也是作為 slave 加入 redis 集群，192.168.30.129 仍然是 master。
Cluster 模式 Cluster 模式介紹
sentinel 模式基本可以滿足一般生產(chǎn)的需求，具備高可用性。但是當(dāng)數(shù)據(jù)量過(guò)大到一臺(tái)服務(wù)器存放不下的情況時(shí)，主從模式或 sentinel 模式就不能滿足需求了，這個(gè)時(shí)候需要對(duì)存儲(chǔ)的數(shù)據(jù)進(jìn)行分片，將數(shù)據(jù)存儲(chǔ)到多個(gè) Redis 實(shí)例中。cluster 模式的出現(xiàn)就是為了解決單機(jī) Redis 容量有限的問(wèn)題，將 Redis 的數(shù)據(jù)根據(jù)一定的規(guī)則分配到多臺(tái)機(jī)器。
cluster 可以說(shuō)是 sentinel 和主從模式的結(jié)合體，通過(guò) cluster 可以實(shí)現(xiàn)主從和 master 重選功能，所以如果配置兩個(gè)副本三個(gè)分片的話，就需要六個(gè) Redis 實(shí)例。因?yàn)?Redis 的數(shù)據(jù)是根據(jù)一定規(guī)則分配到 cluster 的不同機(jī)器的，當(dāng)數(shù)據(jù)量過(guò)大時(shí)，可以新增機(jī)器進(jìn)行擴(kuò)容。
使用集群，只需要將 redis 配置文件中的 cluster-enable 配置打開(kāi)即可。每個(gè)集群中至少需要三個(gè)主數(shù)據(jù)庫(kù)才能正常運(yùn)行，新增節(jié)點(diǎn)非常方便。
cluster 集群特點(diǎn)：
* 多個(gè) redis 節(jié)點(diǎn)網(wǎng)絡(luò)互聯(lián)，數(shù)據(jù)共享
* 所有的節(jié)點(diǎn)都是一主一從（也可以是一主多從），其中從不提供服務(wù)，僅作為備用
* 不支持同時(shí)處理多個(gè) key（如 MSET/MGET），因?yàn)?redis 需要把 key 均勻分布在各個(gè)節(jié)點(diǎn)上， 并發(fā)量很高的情況下同時(shí)創(chuàng)建 key-value 會(huì)降低性能并導(dǎo)致不可預(yù)測(cè)的行為
* 支持在線增加、刪除節(jié)點(diǎn)
* 客戶端可以連接任何一個(gè)主節(jié)點(diǎn)進(jìn)行讀寫(xiě)Cluster 模式搭建
環(huán)境準(zhǔn)備：
三臺(tái)機(jī)器，分別開(kāi)啟兩個(gè) redis 服務(wù)（端口）192.168.30.128 端口：7001,7002
192.168.30.129 端口：7003,7004
192.168.30.130 端口：7005,7006修改配置文件：
192.168.30.128
# mkdir /usr/local/redis/cluster# cp /usr/local/redis/redis.conf /usr/local/redis/cluster/redis_7001.conf# cp /usr/local/redis/redis.conf /usr/local/redis/cluster/redis_7002.conf# chown -R redis:redis /usr/local/redis# mkdir -p /data/redis/cluster/{redis_7001,redis_7002} chown -R redis:redis /data/redis# vim /usr/local/redis/cluster/redis_7001.confbind 192.168.30.128
port 7001
daemonize yespidfile /var/run/redis_7001.pid logfile /usr/local/redis/cluster/redis_7001.log dir /data/redis/cluster/redis_7001 #replicaof 192.168.30.129 6379masterauth 123456
requirepass 123456
appendonly yescluster-enabled yescluster-config-file nodes_7001.conf
cluster-node-timeout 15000# vim /usr/local/redis/cluster/redis_7002.confbind 192.168.30.128
port 7002
daemonize yespidfile /var/run/redis_7002.pid logfile /usr/local/redis/cluster/redis_7002.log dir /data/redis/cluster/redis_7002 #replicaof 192.168.30.129 6379masterauth 123456 requirepass 123456 appendonly yescluster-enabled yescluster-config-file nodes_7002.conf
cluster-node-timeout 15000其它兩臺(tái)機(jī)器配置與 192.168.30.128 一致，此處省略
啟動(dòng) redis 服務(wù)：
# redis-server /usr/local/redis/cluster/redis_7001.conf# tail -f /usr/local/redis/cluster/redis_7001.log# redis-server /usr/local/redis/cluster/redis_7002.conf# tail -f /usr/local/redis/cluster/redis_7002.log其它兩臺(tái)機(jī)器啟動(dòng)與 192.168.30.128 一致，此處省略
安裝 ruby 并創(chuàng)建集群（低版本）：
如果 redis 版本比較低，則需要安裝 ruby。任選一臺(tái)機(jī)器安裝 ruby 即可
# yum -y groupinstall Development Tools # yum install -y gdbm-devel libdb4-devel libffi-devel libyaml libyaml-devel ncurses-devel openssl-devel readline-devel tcl-devel# mkdir -p ~/rpmbuild/{BUILD,BUILDROOT,RPMS,SOURCES,SPECS,SRPMS}# wget http://cache.ruby-lang.org/pub/ruby/2.2/ruby-2.2.3.tar.gz -P ~/rpmbuild/SOURCES# wget http://raw.githubusercontent.com/tjinjin/automate-ruby-rpm/master/ruby22x.spec -P ~/rpmbuild/SPECS# rpmbuild -bb ~/rpmbuild/SPECS/ruby22x.spec# rpm -ivh ~/rpmbuild/RPMS/x86_64/ruby-2.2.3-1.el7.x86_64.rpm# gem install redis # 目的是安裝這個(gè)，用于配置集群# cp /usr/local/redis/src/redis-trib.rb /usr/bin/# redis-trib.rb create --replicas 1 192.168.30.128:7001 192.168.30.128:7002 192.168.30.129:7003 192.168.30.129:7004 192.168.30.130:7005 192.168.30.130:7006創(chuàng)建集群：
我這里是 redis5.0.4，所以不需要安裝 ruby，直接創(chuàng)建集群即可
# redis-cli -a 123456 --cluster create 192.168.30.128:7001 192.168.30.128:7002 192.168.30.129:7003 192.168.30.129:7004 192.168.30.130:7005 192.168.30.130:7006 --cluster-replicas 1Warning: Using a password with -a or -u option on the command line interface may not be safe. Performing hash slots allocation on 6 nodes...
Master[0] - Slots 0 - 5460
Master[1] - Slots 5461 - 10922
Master[2] - Slots 10923 - 16383
Adding replica 192.168.30.129:7004 to 192.168.30.128:7001
Adding replica 192.168.30.130:7006 to 192.168.30.129:7003
Adding replica 192.168.30.128:7002 to 192.168.30.130:7005
M: 80c80a3f3e33872c047a8328ad579b9bea001ad8 192.168.30.128:7001
slots:[0-5460] (5461 slots) master
S: b4d3eb411a7355d4767c6c23b4df69fa183ef8bc 192.168.30.128:7002
replicates 6788453ee9a8d7f72b1d45a9093838efd0e501f1
M: 4d74ec66e898bf09006dac86d4928f9fad81f373 192.168.30.129:7003
slots:[5461-10922] (5462 slots) master
S: b6331cbc986794237c83ed2d5c30777c1551546e 192.168.30.129:7004
replicates 80c80a3f3e33872c047a8328ad579b9bea001ad8
M: 6788453ee9a8d7f72b1d45a9093838efd0e501f1 192.168.30.130:7005
slots:[10923-16383] (5461 slots) master
S: 277daeb8660d5273b7c3e05c263f861ed5f17b92 192.168.30.130:7006
replicates 4d74ec66e898bf09006dac86d4928f9fad81f373
Can I set the above configuration? (type yes to accept): yes # 輸入 yes，接受上面配置 Nodes configuration updated Assign a different config epoch to each node Sending CLUSTER MEET messages to join the cluster可以看到，
192.168.30.128:7001 是 master，它的 slave 是 192.168.30.129:7004；192.168.30.129:7003 是 master，它的 slave 是 192.168.30.130:7006；192.168.30.130:7005 是 master，它的 slave 是 192.168.30.128:7002自動(dòng)生成 nodes.conf 文件：
# ls /data/redis/cluster/redis_7001/appendonly.aof dump.rdb nodes-7001.conf# vim /data/redis/cluster/redis_7001/nodes-7001.conf 6788453ee9a8d7f72b1d45a9093838efd0e501f1 192.168.30.130:7005@17005 master - 0 1557454406312 5 connected 10923-16383
277daeb8660d5273b7c3e05c263f861ed5f17b92 192.168.30.130:7006@17006 slave 4d74ec66e898bf09006dac86d4928f9fad81f373 0 1557454407000 6 connected
b4d3eb411a7355d4767c6c23b4df69fa183ef8bc 192.168.30.128:7002@17002 slave 6788453ee9a8d7f72b1d45a9093838efd0e501f1 0 1557454408371 5 connected
80c80a3f3e33872c047a8328ad579b9bea001ad8 192.168.30.128:7001@17001 myself,master - 0 1557454406000 1 connected 0-5460
b6331cbc986794237c83ed2d5c30777c1551546e 192.168.30.129:7004@17004 slave 80c80a3f3e33872c047a8328ad579b9bea001ad8 0 1557454407366 4 connected
4d74ec66e898bf09006dac86d4928f9fad81f373 192.168.30.129:7003@17003 master - 0 1557454407000 3 connected 5461-10922
vars currentEpoch 6 lastVoteEpoch 0集群操作
登錄集群：
# redis-cli -c -h 192.168.30.128 -p 7001 -a 123456 # -c，使用集群方式登錄查看集群信息：
192.168.30.128:7001 CLUSTER INFO # 集群狀態(tài) cluster_state:ok
cluster_slots_assigned:16384
cluster_slots_ok:16384
cluster_slots_pfail:0
cluster_slots_fail:0
cluster_known_nodes:6
cluster_size:3
cluster_current_epoch:6
cluster_my_epoch:1
cluster_stats_messages_ping_sent:580
cluster_stats_messages_pong_sent:551
cluster_stats_messages_sent:1131
cluster_stats_messages_ping_received:546
cluster_stats_messages_pong_received:580
cluster_stats_messages_meet_received:5
cluster_stats_messages_received:1131列出節(jié)點(diǎn)信息：
192.168.30.128:7001 CLUSTER NODES # 列出節(jié)點(diǎn)信息 6788453ee9a8d7f72b1d45a9093838efd0e501f1 192.168.30.130:7005@17005 master - 0 1557455176000 5 connected 10923-16383
277daeb8660d5273b7c3e05c263f861ed5f17b92 192.168.30.130:7006@17006 slave 4d74ec66e898bf09006dac86d4928f9fad81f373 0 1557455174000 6 connected
b4d3eb411a7355d4767c6c23b4df69fa183ef8bc 192.168.30.128:7002@17002 slave 6788453ee9a8d7f72b1d45a9093838efd0e501f1 0 1557455175000 5 connected
80c80a3f3e33872c047a8328ad579b9bea001ad8 192.168.30.128:7001@17001 myself,master - 0 1557455175000 1 connected 0-5460
b6331cbc986794237c83ed2d5c30777c1551546e 192.168.30.129:7004@17004 slave 80c80a3f3e33872c047a8328ad579b9bea001ad8 0 1557455174989 4 connected
4d74ec66e898bf09006dac86d4928f9fad81f373 192.168.30.129:7003@17003 master - 0 1557455175995 3 connected 5461-10922這里與 nodes.conf 文件內(nèi)容相同
寫(xiě)入數(shù)據(jù)：
192.168.30.128:7001 set key111 aaa
- Redirected to slot [13680] located at 192.168.30.130:7005 # 說(shuō)明數(shù)據(jù)到了 192.168.30.130:7005 上 OK
192.168.30.130:7005 set key222 bbb
- Redirected to slot [2320] located at 192.168.30.128:7001 # 說(shuō)明數(shù)據(jù)到了 192.168.30.128:7001 上 OK
192.168.30.128:7001 set key333 ccc
- Redirected to slot [7472] located at 192.168.30.129:7003 # 說(shuō)明數(shù)據(jù)到了 192.168.30.129:7003 上 OK
192.168.30.129:7003 get key111
- Redirected to slot [13680] located at 192.168.30.130:7005 aaa 192.168.30.130:7005 get key333
- Redirected to slot [7472] located at 192.168.30.129:7003 ccc 192.168.30.129:7003可以看出 redis cluster 集群是去中心化的，每個(gè)節(jié)點(diǎn)都是平等的，連接哪個(gè)節(jié)點(diǎn)都可以獲取和設(shè)置數(shù)據(jù)。
當(dāng)然，平等指的是 master 節(jié)點(diǎn)，因?yàn)?slave 節(jié)點(diǎn)根本不提供服務(wù)，只是作為對(duì)應(yīng) master 節(jié)點(diǎn)的一個(gè)備份。
增加節(jié)點(diǎn)：
192.168.30.129 上增加一節(jié)點(diǎn)：
# cp /usr/local/redis/cluster/redis_7003.conf /usr/local/redis/cluster/redis_7007.conf# vim /usr/local/redis/cluster/redis_7007.confbind 192.168.30.129
port 7007
daemonize yespidfile /var/run/redis_7007.pid logfile /usr/local/redis/cluster/redis_7007.log dir /data/redis/cluster/redis_7007 #replicaof 192.168.30.129 6379masterauth 123456 requirepass 123456 appendonly yescluster-enabled yescluster-config-file nodes_7007.conf
cluster-node-timeout 15000# mkdir /data/redis/cluster/redis_7007# chown -R redis:redis /usr/local/redis chown -R redis:redis /data/redis# redis-server /usr/local/redis/cluster/redis_7007.conf192.168.30.130 上增加一節(jié)點(diǎn)：
# cp /usr/local/redis/cluster/redis_7005.conf /usr/local/redis/cluster/redis_7008.conf# vim /usr/local/redis/cluster/redis_7007.confbind 192.168.30.130
port 7008
daemonize yespidfile /var/run/redis_7008.pid logfile /usr/local/redis/cluster/redis_7008.log dir /data/redis/cluster/redis_7008 #replicaof 192.168.30.130 6379masterauth 123456 requirepass 123456 appendonly yescluster-enabled yescluster-config-file nodes_7008.conf
cluster-node-timeout 15000# mkdir /data/redis/cluster/redis_7008# chown -R redis:redis /usr/local/redis chown -R redis:redis /data/redis# redis-server /usr/local/redis/cluster/redis_7008.conf集群中增加節(jié)點(diǎn)：
192.168.30.129:7003 CLUSTER MEET 192.168.30.129 7007
192.168.30.129:7003 CLUSTER NODES
4d74ec66e898bf09006dac86d4928f9fad81f373 192.168.30.129:7003@17003 myself,master - 0 1557457361000 3 connected 5461-10922
80c80a3f3e33872c047a8328ad579b9bea001ad8 192.168.30.128:7001@17001 master - 0 1557457364746 1 connected 0-5460
277daeb8660d5273b7c3e05c263f861ed5f17b92 192.168.30.130:7006@17006 slave 4d74ec66e898bf09006dac86d4928f9fad81f373 0 1557457362000 6 connected
b6331cbc986794237c83ed2d5c30777c1551546e 192.168.30.129:7004@17004 slave 80c80a3f3e33872c047a8328ad579b9bea001ad8 0 1557457363000 4 connected
b4d3eb411a7355d4767c6c23b4df69fa183ef8bc 192.168.30.128:7002@17002 slave 6788453ee9a8d7f72b1d45a9093838efd0e501f1 0 1557457362000 5 connected
e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 192.168.30.129:7007@17007 master - 0 1557457362729 0 connected
6788453ee9a8d7f72b1d45a9093838efd0e501f1 192.168.30.130:7005@17005 master - 0 1557457363739 5 connected 10923-16383192.168.30.129:7003 CLUSTER MEET 192.168.30.130 7008
192.168.30.129:7003 CLUSTER NODES
4d74ec66e898bf09006dac86d4928f9fad81f373 192.168.30.129:7003@17003 myself,master - 0 1557457489000 3 connected 5461-10922
80c80a3f3e33872c047a8328ad579b9bea001ad8 192.168.30.128:7001@17001 master - 0 1557457489000 1 connected 0-5460
277daeb8660d5273b7c3e05c263f861ed5f17b92 192.168.30.130:7006@17006 slave 4d74ec66e898bf09006dac86d4928f9fad81f373 0 1557457489000 6 connected
b6331cbc986794237c83ed2d5c30777c1551546e 192.168.30.129:7004@17004 slave 80c80a3f3e33872c047a8328ad579b9bea001ad8 0 1557457488000 4 connected
b4d3eb411a7355d4767c6c23b4df69fa183ef8bc 192.168.30.128:7002@17002 slave 6788453ee9a8d7f72b1d45a9093838efd0e501f1 0 1557457489472 5 connected
1a1c7f02fce87530bd5abdfc98df1cffce4f1767 192.168.30.130:7008@17008 master - 0 1557457489259 0 connected
e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 192.168.30.129:7007@17007 master - 0 1557457489000 0 connected
6788453ee9a8d7f72b1d45a9093838efd0e501f1 192.168.30.130:7005@17005 master - 0 1557457490475 5 connected 10923-16383可以看到，新增的節(jié)點(diǎn)都是以 master 身份加入集群的
更換節(jié)點(diǎn)身份：
將新增的 192.168.30.130:7008 節(jié)點(diǎn)身份改為 192.168.30.129:7007 的 slave
# redis-cli -c -h 192.168.30.130 -p 7008 -a 123456 cluster replicate e51ab166bc0f33026887bcf8eba0dff3d5b0bf14cluster replicate 后面跟 node_id，更改對(duì)應(yīng)節(jié)點(diǎn)身份。也可以登入集群更改
# redis-cli -c -h 192.168.30.130 -p 7008 -a 123456192.168.30.130:7008 CLUSTER REPLICATE e51ab166bc0f33026887bcf8eba0dff3d5b0bf14
192.168.30.130:7008 CLUSTER NODES
277daeb8660d5273b7c3e05c263f861ed5f17b92 192.168.30.130:7006@17006 slave 4d74ec66e898bf09006dac86d4928f9fad81f373 0 1557458316881 3 connected
80c80a3f3e33872c047a8328ad579b9bea001ad8 192.168.30.128:7001@17001 master - 0 1557458314864 1 connected 0-5460
4d74ec66e898bf09006dac86d4928f9fad81f373 192.168.30.129:7003@17003 master - 0 1557458316000 3 connected 5461-10922
6788453ee9a8d7f72b1d45a9093838efd0e501f1 192.168.30.130:7005@17005 master - 0 1557458315872 5 connected 10923-16383
b4d3eb411a7355d4767c6c23b4df69fa183ef8bc 192.168.30.128:7002@17002 slave 6788453ee9a8d7f72b1d45a9093838efd0e501f1 0 1557458317890 5 connected
1a1c7f02fce87530bd5abdfc98df1cffce4f1767 192.168.30.130:7008@17008 myself,slave e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 0 1557458315000 7 connected
b6331cbc986794237c83ed2d5c30777c1551546e 192.168.30.129:7004@17004 slave 80c80a3f3e33872c047a8328ad579b9bea001ad8 0 1557458315000 1 connected
e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 192.168.30.129:7007@17007 master - 0 1557458314000 0 connected查看相應(yīng)的 nodes.conf 文件，可以發(fā)現(xiàn)有更改，它記錄當(dāng)前集群的節(jié)點(diǎn)信息
# cat /data/redis/cluster/redis_7001/nodes-7001.conf1a1c7f02fce87530bd5abdfc98df1cffce4f1767 192.168.30.130:7008@17008 slave e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 0 1557458236169 7 connected
6788453ee9a8d7f72b1d45a9093838efd0e501f1 192.168.30.130:7005@17005 master - 0 1557458235000 5 connected 10923-16383
277daeb8660d5273b7c3e05c263f861ed5f17b92 192.168.30.130:7006@17006 slave 4d74ec66e898bf09006dac86d4928f9fad81f373 0 1557458234103 6 connected
b4d3eb411a7355d4767c6c23b4df69fa183ef8bc 192.168.30.128:7002@17002 slave 6788453ee9a8d7f72b1d45a9093838efd0e501f1 0 1557458235129 5 connected
80c80a3f3e33872c047a8328ad579b9bea001ad8 192.168.30.128:7001@17001 myself,master - 0 1557458234000 1 connected 0-5460
b6331cbc986794237c83ed2d5c30777c1551546e 192.168.30.129:7004@17004 slave 80c80a3f3e33872c047a8328ad579b9bea001ad8 0 1557458236000 4 connected
e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 192.168.30.129:7007@17007 master - 0 1557458236000 0 connected
4d74ec66e898bf09006dac86d4928f9fad81f373 192.168.30.129:7003@17003 master - 0 1557458233089 3 connected 5461-10922
vars currentEpoch 7 lastVoteEpoch 0刪除節(jié)點(diǎn)：
192.168.30.130:7008 CLUSTER FORGET 1a1c7f02fce87530bd5abdfc98df1cffce4f1767(error) ERR I tried hard but I can t forget myself... # 無(wú)法刪除登錄節(jié)點(diǎn)
192.168.30.130:7008 CLUSTER FORGET e51ab166bc0f33026887bcf8eba0dff3d5b0bf14
(error) ERR Can t forget my master! # 不能刪除自己的 master 節(jié)點(diǎn) 192.168.30.130:7008 CLUSTER FORGET 6788453ee9a8d7f72b1d45a9093838efd0e501f1
OK # 可以刪除其它的 master 節(jié)點(diǎn) 192.168.30.130:7008 CLUSTER NODES
277daeb8660d5273b7c3e05c263f861ed5f17b92 192.168.30.130:7006@17006 slave 4d74ec66e898bf09006dac86d4928f9fad81f373 0 1557458887328 3 connected
80c80a3f3e33872c047a8328ad579b9bea001ad8 192.168.30.128:7001@17001 master - 0 1557458887000 1 connected 0-5460
4d74ec66e898bf09006dac86d4928f9fad81f373 192.168.30.129:7003@17003 master - 0 1557458886000 3 connected 5461-10922
b4d3eb411a7355d4767c6c23b4df69fa183ef8bc 192.168.30.128:7002@17002 slave - 0 1557458888351 5 connected
1a1c7f02fce87530bd5abdfc98df1cffce4f1767 192.168.30.130:7008@17008 myself,slave e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 0 1557458885000 7 connected
b6331cbc986794237c83ed2d5c30777c1551546e 192.168.30.129:7004@17004 slave 80c80a3f3e33872c047a8328ad579b9bea001ad8 0 1557458883289 1 connected
e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 192.168.30.129:7007@17007 master - 0 1557458885310 0 connected
192.168.30.130:7008 CLUSTER FORGET b4d3eb411a7355d4767c6c23b4df69fa183ef8bc
OK # 可以刪除其它的 slave 節(jié)點(diǎn) 192.168.30.130:7008 CLUSTER NODES
277daeb8660d5273b7c3e05c263f861ed5f17b92 192.168.30.130:7006@17006 slave 4d74ec66e898bf09006dac86d4928f9fad81f373 0 1557459031397 3 connected
80c80a3f3e33872c047a8328ad579b9bea001ad8 192.168.30.128:7001@17001 master - 0 1557459032407 1 connected 0-5460
4d74ec66e898bf09006dac86d4928f9fad81f373 192.168.30.129:7003@17003 master - 0 1557459035434 3 connected 5461-10922
6788453ee9a8d7f72b1d45a9093838efd0e501f1 192.168.30.130:7005@17005 master - 0 1557459034000 5 connected 10923-16383
1a1c7f02fce87530bd5abdfc98df1cffce4f1767 192.168.30.130:7008@17008 myself,slave e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 0 1557459032000 7 connected
b6331cbc986794237c83ed2d5c30777c1551546e 192.168.30.129:7004@17004 slave 80c80a3f3e33872c047a8328ad579b9bea001ad8 0 1557459034000 1 connected
e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 192.168.30.129:7007@17007 master - 0 1557459034427 0 connected保存配置：
192.168.30.130:7008 CLUSTER SAVECONFIG # 將節(jié)點(diǎn)配置信息保存到硬盤(pán) OK
# cat /data/redis/cluster/redis_7001/nodes-7001.conf1a1c7f02fce87530bd5abdfc98df1cffce4f1767 192.168.30.130:7008@17008 slave e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 0 1557458236169 7 connected
6788453ee9a8d7f72b1d45a9093838efd0e501f1 192.168.30.130:7005@17005 master - 0 1557458235000 5 connected 10923-16383
277daeb8660d5273b7c3e05c263f861ed5f17b92 192.168.30.130:7006@17006 slave 4d74ec66e898bf09006dac86d4928f9fad81f373 0 1557458234103 6 connected
b4d3eb411a7355d4767c6c23b4df69fa183ef8bc 192.168.30.128:7002@17002 slave 6788453ee9a8d7f72b1d45a9093838efd0e501f1 0 1557458235129 5 connected
80c80a3f3e33872c047a8328ad579b9bea001ad8 192.168.30.128:7001@17001 myself,master - 0 1557458234000 1 connected 0-5460
b6331cbc986794237c83ed2d5c30777c1551546e 192.168.30.129:7004@17004 slave 80c80a3f3e33872c047a8328ad579b9bea001ad8 0 1557458236000 4 connected
e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 192.168.30.129:7007@17007 master - 0 1557458236000 0 connected
4d74ec66e898bf09006dac86d4928f9fad81f373 192.168.30.129:7003@17003 master - 0 1557458233089 3 connected 5461-10922
vars currentEpoch 7 lastVoteEpoch 0# redis-cli -c -h 192.168.30.130 -p 7008 -a 123456Warning: Using a password with -a or -u option on the command line interface may not be safe.
192.168.30.130:7008 CLUSTER NODES
277daeb8660d5273b7c3e05c263f861ed5f17b92 192.168.30.130:7006@17006 slave 4d74ec66e898bf09006dac86d4928f9fad81f373 0 1557459500741 3 connected
80c80a3f3e33872c047a8328ad579b9bea001ad8 192.168.30.128:7001@17001 master - 0 1557459500000 1 connected 0-5460
4d74ec66e898bf09006dac86d4928f9fad81f373 192.168.30.129:7003@17003 master - 0 1557459501000 3 connected 5461-10922
6788453ee9a8d7f72b1d45a9093838efd0e501f1 192.168.30.130:7005@17005 master - 0 1557459500000 5 connected 10923-16383
b4d3eb411a7355d4767c6c23b4df69fa183ef8bc 192.168.30.128:7002@17002 slave 6788453ee9a8d7f72b1d45a9093838efd0e501f1 0 1557459499737 5 connected
1a1c7f02fce87530bd5abdfc98df1cffce4f1767 192.168.30.130:7008@17008 myself,slave e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 0 1557459499000 7 connected
b6331cbc986794237c83ed2d5c30777c1551546e 192.168.30.129:7004@17004 slave 80c80a3f3e33872c047a8328ad579b9bea001ad8 0 1557459501750 1 connected
e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 192.168.30.129:7007@17007 master - 0 1557459498000 0 connected
可以看到，之前刪除的節(jié)點(diǎn)又恢復(fù)了，這是因?yàn)閷?duì)應(yīng)的配置文件沒(méi)有刪除，執(zhí)行 CLUSTER SAVECONFIG 恢復(fù)。
模擬 master 節(jié)點(diǎn)掛掉：
192.168.30.128
# netstat -lntp |grep 7001tcp 0 0 192.168.30.128:17001 0.0.0.0:* LISTEN 6701/redis-server 1
tcp 0 0 192.168.30.128:7001 0.0.0.0:* LISTEN 6701/redis-server 1
# kill 6701192.168.30.130:7008 CLUSTER NODES
277daeb8660d5273b7c3e05c263f861ed5f17b92 192.168.30.130:7006@17006 slave 4d74ec66e898bf09006dac86d4928f9fad81f373 0 1557461178000 3 connected
80c80a3f3e33872c047a8328ad579b9bea001ad8 192.168.30.128:7001@17001 master,fail - 1557460950483 1557460947145 1 disconnected
4d74ec66e898bf09006dac86d4928f9fad81f373 192.168.30.129:7003@17003 master - 0 1557461174922 3 connected 5461-10922
6788453ee9a8d7f72b1d45a9093838efd0e501f1 192.168.30.130:7005@17005 master - 0 1557461181003 5 connected 10923-16383
b4d3eb411a7355d4767c6c23b4df69fa183ef8bc 192.168.30.128:7002@17002 slave 6788453ee9a8d7f72b1d45a9093838efd0e501f1 0 1557461179993 5 connected
1a1c7f02fce87530bd5abdfc98df1cffce4f1767 192.168.30.130:7008@17008 myself,slave e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 0 1557461176000 7 connected
b6331cbc986794237c83ed2d5c30777c1551546e 192.168.30.129:7004@17004 master - 0 1557461178981 8 connected 0-5460
e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 192.168.30.129:7007@17007 master - 0 1557461179000 0 connected對(duì)應(yīng) 7001 的一行可以看到，master fail，狀態(tài)為 disconnected；而對(duì)應(yīng) 7004 的一行，slave 已經(jīng)變成 master。
重新啟動(dòng) 7001 節(jié)點(diǎn)：
# redis-server /usr/local/redis/cluster/redis_7001.conf192.168.30.130:7008 CLUSTER NODES
277daeb8660d5273b7c3e05c263f861ed5f17b92 192.168.30.130:7006@17006 slave 4d74ec66e898bf09006dac86d4928f9fad81f373 0 1557461307000 3 connected
80c80a3f3e33872c047a8328ad579b9bea001ad8 192.168.30.128:7001@17001 slave b6331cbc986794237c83ed2d5c30777c1551546e 0 1557461305441 8 connected
4d74ec66e898bf09006dac86d4928f9fad81f373 192.168.30.129:7003@17003 master - 0 1557461307962 3 connected 5461-10922
6788453ee9a8d7f72b1d45a9093838efd0e501f1 192.168.30.130:7005@17005 master - 0 1557461304935 5 connected 10923-16383
b4d3eb411a7355d4767c6c23b4df69fa183ef8bc 192.168.30.128:7002@17002 slave 6788453ee9a8d7f72b1d45a9093838efd0e501f1 0 1557461306000 5 connected
1a1c7f02fce87530bd5abdfc98df1cffce4f1767 192.168.30.130:7008@17008 myself,slave e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 0 1557461305000 7 connected
b6331cbc986794237c83ed2d5c30777c1551546e 192.168.30.129:7004@17004 master - 0 1557461308972 8 connected 0-5460
e51ab166bc0f33026887bcf8eba0dff3d5b0bf14 192.168.30.129:7007@17007 master - 0 1557461307000 0 connected可以看到，7001 節(jié)點(diǎn)啟動(dòng)后為 slave 節(jié)點(diǎn)，并且是 7004 的 slave 節(jié)點(diǎn)。即 master 節(jié)點(diǎn)如果掛掉，它的 slave 節(jié)點(diǎn)變?yōu)樾?master 節(jié)點(diǎn)繼續(xù)對(duì)外提供服務(wù)，而原來(lái)的 master 節(jié)點(diǎn)如果重啟，則變?yōu)樾?master 節(jié)點(diǎn)的 slave 節(jié)點(diǎn)。
另外，如果這里是拿 7007 節(jié)點(diǎn)做測(cè)試的話，會(huì)發(fā)現(xiàn) 7008 節(jié)點(diǎn)并不會(huì)切換，這是因?yàn)?7007 節(jié)點(diǎn)上根本沒(méi)數(shù)據(jù)。集群數(shù)據(jù)被分為三份，采用哈希槽 (hash slot)的方式來(lái)分配 16384 個(gè) slot 的話，它們?nèi)齻€(gè)節(jié)點(diǎn)分別承擔(dān)的 slot 區(qū)間是：
節(jié)點(diǎn) 7004 覆蓋 0-5460
節(jié)點(diǎn) 7003 覆蓋 5461-10922
節(jié)點(diǎn) 7005 覆蓋 10923-16383以上是“Redis 集群的示例分析”這篇文章的所有內(nèi)容，感謝各位的閱讀！希望分享的內(nèi)容對(duì)大家有幫助，更多相關(guān)知識(shí)，歡迎關(guān)注丸趣 TV 行業(yè)資訊頻道！
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